I'm about to purchase a SATA hard drive. I was wondering if, aside from the storage capacity, are there any other factors I should keep in mind? I care above all about reliability. Is a more expensive drive less error-prone than a low-end one?
The "enterprise" or "server" drives are more expensive, but have higher estimated MTBF as compared to "consumer" drives. They use higher quality parts. If you compare only "consumer" drives than some price differential really won't tell you much. You usually don't find "enterprise" drives in stores. You usually find them as OEM drives that you can order online or from certain suppliers.
You would hope that a more expensive drive would be made from higher quality components - however, as with all things, that isn't necessarily the case.
Personally I'd go for a brand I recognised, from a supplier I'd trust to replace it if it failed. Computer components tend to fail in one of two ways. Either when you first install them or at the end of a long(ish) life. If you've got a good returns policy to back you up then you've got the first situation covered.
Check the reviews of the ones you are considering. If they're OK products you won't find many, if it's a poor product then you will find people complaining - that's human nature. So the lack of good reviews isn't a bad thing, but the lack of bad reviews is a good thing.
No. Sata is just an interface to a hard disk and most reliability issues with hard disks is related to the actual hard disk and not the interface.
Not necessarily. Sometimes you are paying for the brand name, sometimes for the storage capacity, sometimes for access times (eg AV drives)
If you have the time, read Pinheiro et al (2007) Failure Trends in a Large Disk Drive Population. Proceedings of the 5th USENIX Conference on File and Storage Technologies, Feb 2007. It can be retrieved from http://static.googleusercontent.com/external_content/untrusted_dlcp/labs.google.com/en//papers/disk_failures.pdf
In general, drives of the same manufacturer are make to the same specification in terms of the disk assembly. It is usually the tolerances that differs. To give an example, if you want a paper circle of 5cm diameter, a circle of 4.5 or 5.5 cm maybe acceptable for one use (e.g. home use for decoration of child's room) but a circle of 5.0cm, add or subtract 1mm, (i.e. within 4.9 - 5.1 cm) would be required if it is a decoration project for a project launch for some big, big company.
For example, the load/unload cycle specification of a home drive may be ~ 300,000 times, the load/unload specification of an enterprise drive would be ~ 600,000 times, doubling the figures. The tighter specification also applies to the drive assembly and the disk manufacturing process - and thus the non-recoverable read error rate would be much smaller for enterprise drives, for example, a typical, current home drive - Caviar Black (from Western Digital) would have a nonrecoverable read error per 10^14 bit read. Compare with a typical harddrive manufactured towards datacenter servers WD RE SAS, which would have a nonrecoverable read error per 10^15 bit read. Whether that 10 times more reliability matters to you, is another matter.
To be honest, how you use the drive, is likely more important than which drive you use. Below is a summary of google's findings:
That's how they define it as I understood.
Last but not least, try reading the google paper, it's an excellent read.